What is Building Performance?

Your home is a system, much in the same way your body is a system with parts that perform specific functions. And, much like our bodies, when one system is out of balance, other systems can be affected. There were many assumptions made in the past about how house systems function as a whole, and just as medical science has brought advances in our understanding of human bodies, building science has done the same for our understanding of how buildings perform.

Taking care of the health and performance of our home starts the same way taking care of our bodies does: by having a physical. Before your doctor can give you a diagnosis, he has to have information: your weight, blood count, blood pressure, etc. In the case of your home, that physical is a whole home energy assessment, sometimes referred to as an energy audit, and should be performed by a qualified building analyst or whole home energy rating system rater (HERSII).

The whole home energy assessment or energy audit examines the condition and performance of your homes systems: mechanical, electrical, water heating, fenestration (windows), and building envelope characteristics such as insulation type and density. Detailed measurements are required of every component: area of windows, walls, doors, flooring, and roofing. The square footage and cubic volume of the home has to be determined, along with the type of construction materials utilized. Appliance and lighting information is also gathered.

Combustion safety testing is a critical part of an energy audit, as is the search for hazardous materials like asbestos, gas leaks, and the presence of carbon monoxide. The hazards to humans and pets from combustion appliances can range anywhere from mildly noxious to deadly, especially if the wrong set of circumstances exists in a home. Assessing whether there is adequate combustion ventilation air for each appliance, whether the combustion by-products are properly vented to the outside of the home, and running worst-case scenarios to test that combustion gasses cannot be back-drafted from ventilation flues are performed.

If a home passes combustion safety and hazardous materials are not present, diagnostic tests with calibrated instruments are performed following set testing protocols and standards. These tests may include, but are not limited to, blower door tests that test for building leakage, and duct blaster tests that test for leakage in ventilation ducting.

All of the measurements and test results are compiled, and entered into state-approved modeling software. The vintage of the home, the measurements gathered, appliance efficiency ratings, lighting wattages, construction materials, diagnostic test results, and 12-18 months of utility data (if available) are input. This software has underlying databases and mathematical algorithms that take all of the specific information about the home, and outputs an energy consumption profile of that home. In California, that profile is called an “ECON-2” report.

This energy consumption profile or ECON-2 report is useful to homeowners to identify where their energy dollars are being spent. The existing home’s profile is the baseline for identifying where energy savings can be realized, and how much savings could be anticipated from each measure. The modeling software allows energy upgrade scenarios to be developed to determine where the maximum savings can be realized.

In building performance, results matter. They don’t just matter, they are measured and verified. In this way, building performance is different than any other construction trade. There is a “test-in” and “test-out” process to ensure that promised results are achieved.